The invention relates generally to excavating machines of the type having a device for cutting the earth including, but not limited to, bucket wheel trenchers, chain bar trenchers, trencher or trenchless plows and hoes, vibratory plows, disc wheel cutters, drum cutters, etc., and more particularly to a lift arm assembly for raising and lowering the earth cutting device and for providing downward pressure on the earth cutting device during use.
Excavating machines are well known for use in the cutting of an open trench having either vertical or sloped walls for the purposes of land drainage and irrigation including agricultural tiling, as well as the installation of utilities such as cable lines, pipelines, water lines, sewer lines, etc. These excavating machines are often of a vehicular type being self-contained and suitably driven for either over-the-road travel or movement during use of the earth cutting device.
Typically, the excavating machines of the prior art have used a set of slides or beams to raise and lower the earth cutting device, however, these machines rely on gravity to hold the earth cutting device down during use. There just isn't enough weight on the earth cutting device. These machines generally operate with difficulty due to the tendency of the earth cutting device to ride on, rather than penetrate into, the surface being worked on. This riding tendency results in appreciable bouncing of the machine and instability in its operation. In addition, this riding tendency results in a less than desirable rate of speed. Higher horsepowers are wasted if the earth cutting device is not effectively penetrating the surface being worked on. Efficiency is extremely important to the operators of these machines as inefficient operation costs time and, in turn, money.
The difficulties encountered in the prior art discussed hereinabove are substantially eliminated by the present invention.